ES2394191T3 - Cooking range with at least one heating zone of several heating elements - Google Patents

Abstract

Cooking range with at least one heating zone (20, 22) of several heating elements (10), a user interface (26) for setting a heating power of the heating zone (20, 22), and with a control unit (18) for operating the heating elements (10) and for distributing the heating power between the heating elements (10) according to a distribution of the heating power, where the control unit (18) is configured to determine the distribution of the heating power at least in a manner dependent on the adjusted heating power, characterized in that the control unit (18) is configured to, in case of heating powers below a threshold value, distribute the heating power between a number of heating elements (10) greater than in case of decay powers above the threshold value.

Description

Cooking range with at least one heating zone of several heating elements

The invention relates to a cooking field with at least one heating zone of several heating elements according to the general concept of claim 1, and to a method for operating such a cooking field according to the general concept of claim. 12.

From FR 2 863 039 A1 an induction cooking field is known with a plurality of inductors, which are arranged in a grid. A control unit detects cooking battery elements that are placed on the induction cooking field, and defines for each cooking battery element a heating zone of several heating elements. The shape, size and position of the heating zone are adapted to the shape, size and position of the cooking battery element. The user can adjust through a user interface a heating power of each of the heating zones, and the unit of

15 command drives the heating elements in such a way that the desired heating power is distributed among the heating elements, that is, inductors, according to a predetermined heating power distribution.

For this, the control unit determines for each inductor in the heating zone a degree of overlap. The degree of overlap corresponds to a portion of the inductor that is overlapped by a base of the detected cooking battery element. The distribution of the heating power then occurs essentially in the proportion of the degrees of overlapping, so that inductors at the edge of the heating zone that are only incompletely overlapping are provided with a heating power less than a inductors completely overlapping. In this way, radiation losses are reduced at the edge of the area of

25 heating.

In practice, the process known from FR 2 863 039 A1 is very expensive. Due to the reduced heating power of the inductors at the edge of the heating zone, the process also leads to a non-homogeneous surface heating power. The operation of the inductors at the edge of the heating zone with reduced heating power also leads to higher connection and conduction losses proportionally in induction cooking field inverters that generate a high frequency heating current to drive the inductors

In large heating zones with many heating elements, in case of power

High heating, an available heating power, which is generally limited by the power available in the domestic power network, is distributed among all heating elements. If the number of the heating elements exceeds a critical value, all the heating elements can therefore be operated with only a fraction of their maximum power. However, connection losses and ohmic losses increase with the number of heating elements, so that the degree of efficiency is reduced overall.

The task of the invention consists in particular in providing a higher degree of efficiency to a generic cooking field, where at the same time a heating power of the homogeneous surface must be attainable.

The task is solved according to the invention by the features of the independent claims, while advantageous improvements and improvements of the invention can be extracted from the secondary claims.

The invention is based in particular on a cooking field with at least one heating zone of several heating elements, a user interface for adjusting a heating power of the heating zone, and with a control unit for operating the heating elements. heating and to distribute the heating power among the heating elements according to a distribution of the heating power.

55 It is proposed that the control unit be configured to determine the distribution of the heating power in a manner dependent on at least one size of the heating zone and / or the adjusted heating power. Through this, the distribution of the chosen heating power can be adapted to the real needs, which can be very different at different intervals of the heating power. In general, the user desires, in the case of high heating power values, a rapid heating of the cooking battery element and its contents. Therefore, in this case, lost powers should be reduced as much as possible, so that a large part of the nominal power of the cooking field, that is, of the heating zone, can be used. A degree of efficiency of the cooking field in the coupling of the heating power in the cooking battery element should be optimized. On the other hand, in case of lower heating powers, the degree of efficiency is lower

65 importance, so that the distribution of the heating power in this case can be chosen according to a heating power of the surface as homogeneous as possible.

The control unit can be configured both through suitable software, and through suitable hardware for the selection according to the invention of the distribution of the heating power. For this, the control unit may comprise, by way of example, a memory with different distributions of the heating power. Alternatively or complementary to this, the control unit may be

5 implemented a parametric function to determine the distribution of the heating power which, together with the heating power, can also depend on other parameters, especially the size and geometry of the heating zone.

The advantages of the invention are especially effective then if the heating elements are inductors, or

10 that is, if the cooking field is an induction cooking field. The heating power of the inductors is coupled very directly to the cooking battery element, and the rapid response times allow a flexible distribution of the heating power between the inductors.

In an improvement of the invention, it is proposed that the heating elements be arranged in a

15 uniform grid, and that the control unit is configured to detect a cooking battery element, and to gather in a heating zone heating elements that are at least partially overlapped by the cooking battery element. In such matrix or micromodule cooking fields, the question of the distribution of the heating power is of special relevance for the degree of efficiency of the cooking field, so that there is here a particularly high improvement potential.

Alternatively, the invention can also be used in cooking fields in which the heating elements of the heating zone are concentrically arranged, where at least one annular heating element surrounds at least one central heating element.

25 A concentration of the available and, generally limited, heating power of the cooking range or of the heating zone in the most important heating elements with the highest degree of efficiency can be achieved, if the control unit is configured to, in case of heating powers below a threshold value, distribute the heating power among a number of heating elements greater than in case of heating powers above the threshold value. Above the threshold value, they can be

30 the heating elements that can only be operated with large losses or that contribute little to heat the cooking battery element in comparison with other heating elements are disconnected.

Since such heating elements are often arranged at the edge, it is further proposed that the

The control unit is configured to, in the case of heating powers below the threshold value, further activate the heating elements used for heating powers above the threshold value at least one heating element that is arranged at an edge of The heating zone.

40 A higher concentration of the available heating power can be achieved if the control unit is configured to, in case of heating powers below the threshold value, further activate the heating elements used for heating powers above the value threshold at least one heating element that is surrounded on at least three sides by other heating elements of the same heating zone.

45 Further adaptation and optimization of the heating power distribution can be made possible if the control unit is configured to detect a cooking battery element placed over the heating zone, and determine the distribution of the heating power in a manner dependent on the size and / or the material of the cooking battery element.

According to another aspect of the invention, it is proposed that the control unit be configured to choose the distribution of the heating power of at least two different heating power distributions.

Since, in very small heating zones, the degree of efficiency can only be slightly improved by

55 adaptation of the heating power distribution, it is proposed that the control unit be configured to determine the distribution of the heating power in a manner dependent on the heating power set only then if the heating zone comprises at least five elements heating In these cases, the complexity of command and additional regulation can be reduced.

60 A time-dependent heating power distribution can be carried out if the control unit is configured to use a different heating power distribution in a heating phase of a cooking process than in at least a second phase , following the heating phase. In the second phase, the distribution of the heating power can then be optimized, for example, in relation to the heating power of the homogeneous surface.

Another aspect of the invention relates to a method for operating a cooking field with at least one heating zone of several heating elements, in a manner dependent on a heating power adjusted through a cooking field user interface. , where the heating power is distributed among the heating elements according to a distribution of the power of

5 heating.

It is proposed that the distribution of the heating power be determined in a manner dependent on at least one size of the heating zone and / or the adjusted heating power. Through such a control, the efficiency of the cooking field can be improved especially in case of high heating powers in the range of a nominal cooking field power.

Other advantages are taken from the following description of the drawing. Examples of embodiment of the invention are shown in the drawing. The drawing, description and claims contain numerous features in combination. The person skilled in the art will consider the characteristics advantageously also separately, and the

15 will gather in other reasonable combinations.

They show: Fig. 1 a cooking field with a plurality of heating elements and a control unit, according to a first configuration of the invention,

Fig. 2 the heating elements of a heating zone of the cooking field of Figure 1 with a distribution of the heating power used for low heating powers,

Fig. 3 the heating elements of the heating zone of Figure 2 with a distribution of the heating power used for higher heating powers,

Fig. 4 the heating elements of a smaller heating zone of the cooking field of Figure 1 with a distribution of the heating power used for low heating powers,

Fig. 5 the heating elements of the heating zone of Figure 4 with a distribution of the heating power used for higher heating powers,

Fig. 6 a heating zone with concentric heating elements, according to an alternative configuration of the invention,

Fig. 7 a bridge grill heating zone in a cooking field, according to another alternative configuration of the invention,

Fig. 8 a grill heating zone in a cooking field, according to another alternative configuration of the invention,

Fig. 9 a dependence on the frequency of a heating power for two distributions of the heating power different from a heating zone and Fig. 10 a dependence on the power of a heating current for two distributions of the heating power different from a heating zone.

Figure 1 shows a cooking field with a plurality of heating elements and a control unit 18, according to a first configuration of the invention. The heating elements are inductors 10, which are distributed in a regular two-dimensional grid across the entire surface of the cooking field.

The inductors 10 are covered by a cover plate 12 of glass or ceramic hob, on which cooking battery elements 14, 16, such as cooking pots or pans, can be placed. To detect the elements

55 of the cooking battery 14, 16, the control unit 18 generates low voltage measuring currents, which flow through the inductors 10, or the oscillating circuits comprising the inductors 10. If a cooking battery element 14, 16 overlaps one of the inductors 10 completely or partially, this influences the inductance of this inductor 10. When this happens, the magnitude of the inductance change is related to the degree of overlap. Likewise, also the losses of eddy currents at the base of the cooking battery element 14, 16 influence the attenuation of the oscillating circuit. Therefore, the control unit 18 can determine from the oscillating properties of the oscillating circuit the presence and degree of overlapping of the cooking battery element 14, 16, and also draw conclusions about material properties of the battery element. of cooking 14, 16, that is, on properties of the material of its base.

65 After the detection of a cooking battery element 14, 16, the control unit 18 gathers those inductors 10 that overlap by the base of the cooking battery element 14, 16 in at least a certain degree of overlap in a zone heating 20, 22 adapted in size, shape and position to the cooking battery element 14, 16.

The cooking field comprises a user interface 26 with various adjustment elements 28 and a display 24.

5 The heating zone 20, 22 determined in the manner described above is represented in the display 24 as a pictogram, depending on the shape of the cooking battery element 14, 16, by way of example, as a circle, oval or rectangle, so that the user has an overview on the heating zones 20, 22 active.

Through the adjustment elements 28 of the user interface 26, the user can finally adjust a heating power for each of the heating zones 20, 22. For this, the user adjusts a degree of power that can be adopted , for example, integer and half-line values between 0 and 9. The control unit 18 converts the degree of power into a heating power, and drives the inductors 10 in such a way that in the inductors 10 of the heating zone 20, 22 in question the desired heating power is consumed together.

15 To this end, the hand unit 18 connects the inductors 10 of the heating zone 20, 22 with one or more inverters 32 of a construction group of the power electronics of the cooking field by actuating a switch arrangement 30. The inverters 32 comprise unipolar semiconductor switches 34, which in the exemplary embodiment are configured as transistors with insulated gate electrode (IGBT) with diode connected in parallel. The semiconductor switches 34 arranged in a semipuent configuration are each connected to a pole of a rectifier 36, which is connected through a filtering circuit 38 with a phase 40 of a home current network.

The heating current generated by inverters 32 with a frequency, which is found

25 approximately in the range between 75 kHz and 100 kHz, it generates in the inductors 10 a rapidly changing magnetic field, which causes eddy currents in the ferromagnetic base of the cooking battery element 14, 16. The eddy currents finally generate heat in this base. The frequency of the heating current is above a resonance frequency of the complete system comprising the inductor 10, a resonance capacitor not shown here, and the base of the cooking battery element 14,

16. With increasing frequency, fewer and fewer Weiss domains in the ferromagnetic base of the cooking battery element 14, 16 can follow the alternating magnetic field, so that the power dissipation and, thereby, the heating power, decreases . Therefore, by varying the frequency of the heating current, the heating power coupled by the inductors 10 at the base of the cooking battery element 14, 16 can be adjusted by the control unit 18. Also, the control unit 18 can connect and

35 disconnect the inductors 10 periodically to reach a desired average heating power on a temporary basis.

Starting from the heating power determined from the input in the user interface 26, the control unit 18 now chooses a distribution of the heating power. This choice depends on the size of the heating zone 20, 22, or on the cooking battery element 14, 16, on the properties of the base material of the cooking battery element 14, 16, on the number of inverters. 32 available to drive the inductors 10 of the heating zone 20, 22, and of the desired heating power. The distribution of the heating power sets the fraction, consumed by the individual inductors 10, of the heating power of the entire heating zone 20, 22. In the simplest case, the power distribution

45 heating is a uniform distribution. The heating power is then divided by the number of the inductors 10 of the heating zone 20, 22 to calculate the fraction of each individual inductor.

In a particularly advantageous configuration of the invention, the control unit 18 distributes, in the case of heating powers below a threshold value, the heating power between a number of inductors 10 greater than in the case of heating powers above This threshold value.

Figure 2 shows the heating elements of a heating zone 20 of the cooking field of Figure 1 with a distribution of the heating power used for low heating powers. In the embodiment shown in Figure 2, the heating zone 20 is formed by all

55 inductors 10 which are overlapped by the cooking battery element 14, 16 by at least 40%. If the user chooses a heating power below the threshold value, all inductors 10 of the heating zone 20 are driven to achieve a heating power as homogeneous as possible. The heating power is then distributed evenly among all the inductors 10 of the heating zone 20. Different scratches indicate that the inductors 10 in question are fed by different inverters 32.

Figure 3 shows the heating elements of the heating zone 20 of Figure 2 with a distribution of the heating power used for higher heating powers. For heating powers above the threshold value, an inductor 10 or several inductors 10a, 10b are deactivated. The 65 active inductors 10 are shown scratched, and the inductors 10a, 10b deactivated, as empty circles with thicker edge line. The control unit 18 disconnects at least one inductor 10a, which is arranged

at one edge of the heating zone 20. For very large heating zones 20, the control unit 18 further disconnects at least one inductor 10a that is surrounded at least on three sides by other inductors 10a of the same heating zone 20. The heating power is then distributed among the remaining active inductors 10 in equal parts.

5 Thus, conduction losses and ohmic dispersion losses through inductors 10 partially overlapped at the edge of the heating zone 20 can be reduced on the one hand and, on the other hand, the remaining inductors 10 can be driven with a lower heating frequency, so that in the inverters 32 less connection processes can be carried out per time space and, thus, a lower energy consumption. The energy required for the connection processes can be greatly reduced, since the inverters 32 can be operated in the resonance range of the oscillating circuits comprising the inductors 10.

Therefore, the control unit 18 selects with each predetermined cooking pot with a position

15 determined the distribution of the heating power of at least two different heating power distributions. The distribution of the heating power is a standardized distribution function, which selects percentage fractions of individual inductors of the total heating power of the heating zone 20. According to the first distribution of the heating power, the heating power is distributed evenly among all the inductors 10 and, according to the second distribution of the heating power, the heating power is uniformly distributed only among a part of the inductors 10.

If a heating zone comprises less than five heating elements, the heating power is always evenly distributed among the heating elements, since the complexity of

25 additional command in this case would not be justified.

In an alternative configuration of the invention, the control unit 18 is configured by means of timing and appropriate software to use a different heating power distribution in a heating phase of a cooking process than in at least one phase. following the heating phase. In particular, it is conceivable to use a different threshold value in the heating phase, which can last approximately 2 minutes, to switch between different distributions of the heating power after the end of the heating phase, so that this threshold value can be configured in a time dependent manner.

Figure 4 shows the inductors 10 of a smaller heating zone 22 of the cooking range of the

Figure 1 with a distribution of the heating power used for small heating powers, in which the heating power is uniformly distributed among all inductors 10 of the heating zone 22.

Figure 5 shows the heating elements of the heating zone 22 of Figure 4 with a distribution of the heating power used for higher heating powers, in which four inductors 10 arranged at the edge of the heating zone 22 they are disconnected in order to drive the remaining inductors 10 with a greater degree of efficiency.

Figure 6 shows a heating zone 22 with concentric inductors 10 according to a configuration

Alternative of the invention. The heating zone 22 comprises two concentrically arranged inductors 10, where an annular inductor 10a surrounds a central, circular inductor 10b. The outer, annular inductor 10a is connected to larger pots and, with high heating powers, generates most of the heating power. Naturally, the invention can be easily generalized to heating zones with three or more concentric heating elements.

Figure 7 shows a heating zone 22 of bridge grill in a cooking field according to another alternative configuration of the invention. Two round inductors 10a, 10b can be connected by a third inductor 10c in an elongated heating zone 22, which can be used to heat a large grill. The control unit 18 of this cooking field distributes the heating power, depending on the

55 detected size and position of the grill and the adjusted power level, between the inductors 10a, 10b, 10c.

Figure 8 shows a grill heating zone 22 in a cooking field according to another alternative configuration of the invention. A round inductor 10a can be extended by another inductor 10b to an elongated grill heating zone 22.

Figure 9 shows a frequency dependence of a heating power for two different heating power distributions of a heating zone 20. The upper, continuous line corresponds to a uniform distribution among all inductors 10 of the type represented in Figure 2, and the bottom, broken line, corresponds to a concentration in a lower number of inductors 10 of the type depicted in Figure 3. It is recognizable that the same heating power can be achieved with a lower number of heating elements with a lower frequency of the heating current. In addition, the frequency is

It is closer to the resonance frequency of the system, which corresponds to the maximum of the curves. Therefore, it is recognizable that, by deactivating individual inductors 10, connection losses can be reduced.

5 Figure 10 shows a dependence on the power of a heating current for two distributions of the heating power different from a heating zone 20, 22. With equal heating power, in case of the higher number of inductors 10 are necessary higher current values, which leads to greater ohmic losses in semiconductor switches 34 of inverters 32.

10 The control unit 18 is a universally programmable calculation unit, in which a method for operating a cooking field with at least one heating zone 20, 22 of several heating elements is implemented. The operation takes place in a dependent manner of a heating power set through a user interface 26 of the cooking field, where the heating power is distributed according to a distribution of the heating power between the heating elements.

15 heating, and the distribution of the heating power is adapted to the heating power.

Reference symbols

10 Inductor 20 10a Inductor 10b Inductor 25 10c Inductor 12 Cover plate 14 Cooking battery element 30 16 Cooking battery element 18 Control unit 35 20 Heating zone 22 Heating zone 24 Display 40 26 User interface 28 setting 45 30 Switch arrangement 32 Inverter 34 Semiconductor switch 50 36 Rectifier 38 Filtering circuit 55 40 Phase

Claims (10)

1. Cooking range with at least one heating zone (20, 22) of several heating elements (10), a user interface (26) to adjust a heating power of the heating zone (20, 22), and with 5 a control unit (18) for operating the heating elements (10) and for distributing the heating power between the heating elements (10) according to a distribution of the heating power, where the control unit (18 ) is configured to determine the distribution of the heating power at least in a manner dependent on the adjusted heating power, characterized in that the control unit (18) is configured for, in case of heating powers below a threshold value , distribute the 10 heating power between a number of heating elements (10) greater than in case of heating powers above the threshold value. 2. Cooking field according to claim 1, characterized in that the heating elements (10) are inductors fifteen 3. Cooking field according to one of the preceding claims, characterized in that the heating elements (10) are arranged in a uniform grid, and that the control unit (18) is configured to detect a cooking battery element (14, 16), and gathering in the heating zone (20, 22) those heating elements (10) that are at least partially overlapped by the battery element of 20 cooking (14, 16). 4. Cooking field according to one of claims 1 or 2, characterized in that the heating elements of the heating zone (20, 22) are concentrically arranged, where at least one annular heating element (10a) surrounds at least one central heating element (10b). 5. Cooking field according to claim 4, characterized in that the control unit (18) is configured to, in case of heating powers below a threshold value, additionally use the heating elements (10) used for powers of heating above the threshold value at least one heating element (10b) that is disposed at an edge of the heating zone (20, 22). 6. Cooking field according to one of the preceding claims, characterized in that the control unit (18) is configured to, in case of heating powers below the threshold value, additionally use the heating elements used for power powers of heating above the threshold value at least one heating element that is surrounded by at least three sides by other elements of 35 heating of the same heating zone (20, 22). 7. Cooking field according to one of the preceding claims, characterized in that the control unit (18) is configured to detect a cooking battery element (14, 16) placed on the heating zone (20, 22), and determine the distribution of heating power in a manner dependent on 40 size and / or the material of the cooking battery element (14, 16). 8. Cooking field according to one of the preceding claims, characterized in that the control unit (18) is configured to choose the distribution of the heating power of at least two different heating power distributions. 9. Cooking field according to one of the preceding claims, characterized in that the control unit (18) is configured to determine the distribution of the heating power in a manner dependent on the heating power set only then if the heating zone (20, 22) comprises at least five heating elements (10). 10. Cooking field according to one of the preceding claims, characterized in that the control unit (18) is configured to use a different heating power distribution in a heating phase of a cooking process than in at least one phase following the heating phase. 55 11. Procedure for operating a cooking field with at least one heating zone (20, 22) of several heating elements (10), depending on a heating power set via a user interface (26) of the cooking field, where the heating power is distributed among the heating elements (10) according to a distribution of the heating power, characterized in that the distribution of the heating power is determined in a dependent manner of at least one size of the 60 heating zone (20, 22) and / or of the adjusted heating power, where in case of heating powers below a threshold value, the heating power is distributed among a larger number of heating elements (10) that in case of heating powers above the threshold value.